I would personally recommend Evo X. It's straight forward and get's the job done.
Xbox Media Centre can be used as well but again, personally, i would stick with Evo X as your main dash and run XBMC as a program.

Unleash X has potential as it looks really pretty when you have all the preview video's load up as you highlight a game. But then again, your going to have to download videos of each game and place it in the game directory. If your into good looking interfaces than Unleash X might be your kettle of fish, though id have to say the best of both worlds (or a happy medium) is XBMC; it looks good and its very functional.

Another thing; you can put the dashboards on your xbox and try them out, if put in the programs directory for instance, they'll appear in the programs list in Evo X. If your happy enough with a different one than you can make it your default dash if you like. Xbox-Scene.com has all the information you need to do pretty much anything with the old black box.

The UnleashX dashboard is only intended for modified Xbox consoles. Any modification, including software mods that can be installed without opening the console, will void your warranty. It is also possible that it can completely break your console, although this is very unlikely if you are careful and follow all instructions. It should be noted that the Xbox is now out of warranty, since Microsoft no longer supports it.

What does this mean and should I worry about it?

Also, can you directly put Xbox ISOS into the Xbox via FTP without the need of burning them to discs?

The UnleashX dashboard is only intended for modified Xbox consoles. Any modification, including software mods that can be installed without opening the console, will void your warranty. It is also possible that it can completely break your console, although this is very unlikely if you are careful and follow all instructions. It should be noted that the Xbox is now out of warranty, since Microsoft no longer supports it.

What does this mean and should I worry about it?

Also, can you directly put Xbox ISOS into the Xbox via FTP without the need of burning them to discs?

Click to expand...

I had Unleash X on my xbox, but not as a default dashboard so i cant answer that for sure, but id look at that statement on wiki as a deterrent to those looking to mod their xbox.
Rather than worry about it why not try out Unleash X with Evo X as your default dash. I wasn't too impressed with Unleash X to be honest with you so i'd see if you like it first.

And yes, you can directly FTP ISO's to the xbox via flashfxp or any ftp client you like. When you boot up Evo X for instance you see the xbox's IP address in the top corner of the screen; (assuming you don't have any problems with networking) enter that into your ftp client with username & pass (which is normally just "xbox" for both, but you can change it) and you can copy content over.

I remember using a program that would specifically extract the ISO to the xbox, which i haven't used in a while. Which is easier than extracting the ISO yourself and then copying it over. I think the program was called Qwix, though i used one or two others as well.

Check xbox-scene.com. To me that is in itself the best modded xbox wikipedia.